Electrical liquid treating device



Nov. 28, 1950 w. DUBILIER ELECTRICAL LIQUID TREATING DEVICE 2 Sheets-Sheet 1 Filed June 5, 1945 Nov. 28, 1950 w. DUBILIER ELECTRICAL LIQUID TREATING DEVICE 2 Sheets-Sheet 2 Filed June 5, 1945.

INVEN'ToR. I?

Will/am D nllfrllllllilIlflllllllllllllllllf.lill! A ATTORNEY Patented Nov. 28, l1950 UNITED STATES PATENT OFFICE ELECTRICAL LIQUID TREATING DEVICE William Dubilier, New Rochelle, N. Y.

Application June 5, 1945, Serial No. 597,695

6 Claims.

The present invention relates to devices for the treatment of Water to reduce or eliminate the eiects of hardness thereof, such as for the prevention of scale in boilers, pipelines, etc., and to prevent other defects due to the presence of mineral matter and other impurities in the ordinary water supply. ,n More particularly, the invention is concerned with treating devices of this character wherein the water is passed on its way to the consumer Abetween a pair of electrodes maintained at a predetermined potential difference low enough to avoid corrosion effects or electrodeposition by electrolysis or other chemical action.

According to known arrangements of this type such as described, for instance, in U. S. Patent No. 2,207,583, the water is conveyed on its way to the consuming means, substantially without chemical change, over a rst electrode (anode) connected to the positive pole of a unidirectional current source of a voltage of the order below about 12 millivolts, said source having its negative pole connected to a cooperating electrode (cathode) also exposed in Contact with the water.

The actual phenomena taking place and function underlying this method of conditioning or treating water are not yet fully understood. It appears, however, that thev action taking place is of an essentially physical rather than chemical nature on account of the low treating voltage ,or current densities used, precluding electrolysis or other chemical action.

According to one possible explanation, the ions o i the salts or other impurities present or dissolved in the water, in coming in Contact with or in close proximity to the electrodes, are charged at least in part so as to become neutral particles, whereby to prevent their later precipitation in the form of a regular or crystalline scale structure, so as to result, in the case of a boiler or heating device, in an amorphous or mud-like deposit which can be easily removed. A similar effect may be caused by the electric current itself passing through the water from one electrode to the other, which explains the possibility of using both alternating current (A. C.) and direct current (D. C.) voltage, though the latter has been found to produce better and more consistent results in practice. In any case, it is evident that the treating voltage should be suiiciently low to prevent movement or attraction of the salt ions or particles towards the electrodes to avoid decomposition or deterioration of the electrode material and other undesirable chemical eiects.

.This neutralization or charging of the ion particles present in s-o-called hard water has been found to produce other desirable effects in connection with various uses of water thus treated, in particular in reducing the amount of soap required to produce a good lather and in prevent- A ing the formation of a curd or smudge resulting" in the well-known bathtub rings and other un'- desirable eiects directly due to the hardness of the water being used.

Among the objects of the present invention is the provision of` a water-treating device of the above character to reduce or prevent the effects of hardness which is both simple in design and'u easy and efficient in use; which is inexpensive to manufacture; which can be easily and quickly installed; which may be used in connection with any type of water or degree of hardness thereof; and

which is inexpensive in use and reliable in operation throughout its life.

In water-treating apparatus of the above type, it is customary to use a separate battery or small Y` a particular size of apparatus and type of waterv to be treated, the correct treating potential dif ference between the electrodes may be obtained and readjusted from time to time to maintain the optimum eiciency of the device.

Since, however, the quality or hardness of the ,v water diiers in different locations, and evenvaries from time to time at the same location, a

constant supervision and readjustment is required f to insure full loperating eiciency at all times.

A further object of the invention is, therefore,

to provide an improved treating apparatus of the above-mentioned character 4which may be prefabricated in such a manner as to result in a proper treating voltage substantially independently of the location or characteristics of the water being treated and substantially without requiring any special adjustments and supervision during use.

Another object of the invention is to provide a water-treating device of this character of simplied design and suitable for use in the home by enabling its easy and quick attachment to an I ordinary water faucet for various purposes Such as to improve the solubility of soaps and to reduce or eliminate other defects due to the hardness in f existing water supplies.

Other objects and novel aspects of the invention will in part be pointed out and in part become apparent as the following detailed description proceeds, taken in reference to the accompanying drawings forming part of this specication, and wherein:

Figure 1 is a cross-sectional view through a water-treating device embodying the principles of the invention and designed for manual adjustment and control of the treating voltage;

Figure 2 shows a modied and improved device of this type wherein different characteristics of the water to be treated are automatically taken into account, substantially without adjustment and supervision;

Figure 3 is a cross-section through a simplied treating unit of small size suitable for direct attachment to a household water faucet;

Figure 4 shows a modification of a unit according to Figure 3, embodying means for automatically compensating for different degrees of hardness and/or other characteristics of the Water to be treated;

rFigure 4A is a fractional View of Figure 4 showing a further modification of the invention;

Figures 5 and 6 are cross-sections of further simplied small-size treating units constructed in accordance with the invention; and

Figure 7 is a fractional view showing still another modiication of an automatically compensated treating device constructed in accordance with the principles of the invention.

Like reference numerals identify like parts throughout the different views of the drawings.

Referring more particularly to Figure l, the reference numeral IB represents a hollow cylindrical housing or tubular electrode advantageously serving as the cathode of the device and which may be directly inserted in a supply water conduit by means of suitable jointsor connecting members I i and I2, all of which may be of standard design, to pass water from a supply source to a consumer, as indicated by the arrows in the drawing.

Mounted concentrically within the electrode IB isa further hollow cylindrical and suitably apertured or perforated inner electrode or anode I3 electrically isolated from the electrode I@ and arranged in such a manner that the water will pass through the device exposed in contact with both electrodes, and that as much as possible of the water will come in contact with the electrodes for the reason which will become obvious from the following.

In the construction shown, the electrode I3 which may be formed from perforated sheet metal bent and riveted or otherwise connected together at the overlapping edges, is mounted by the provision of a cup-shaped supporting or reinforcing member Ill snugly fitting within its upper end and rigidly connected thereto by riveting or in any other suitable manner. The electrode I3 is held in spaced relation from the outer electrode by a pair of diametrically disposed spacing members or insulating washers I5 and I 6 and connected or secured to the outer electrode or tube I0 by means of bolts I'I and It'. The latter are insulated from the electrode II) by means of insulating washers 2U and 2I, each having a depending sleeve portion Surrounding the bolts Il and I8 and fitting within suitable bores in the outer tube. Bolt I1 is suitably provided with a pair of terminal nuts 22 and 23 for securing a connecting wire'or'lead leading to a 4 battery or the like in the manner shown and described in detail hereafter.

A cooperating terminal post for the outer electrode ii) is provided in a similar manner consisting of a threaded stud 26 engaging a tapped hole of electrode It and cooperating clamping nuts 25 and 25 for securing a further wire or lead connected to the opposite pole of the battery or other voltage-supply source.

The lower end of the inner electrode I3 is spaced and insulated from the outer electrode by the provision of a further ring-shaped insulating spacer 2l held in place by crimping or spinning overthe edge of the electrode I3 in the manner shown at 2S in the drawing.

Suitable operating potential difference is applied to the electrodes I El (cathode) and I3 (anode) from a dry cell 39 or other source of supply voltage connected by suitable leads or wires to the electrode terminal posts, as shown, in series with an adjustable resistor SI of the wire-wound or any other suitable type, and a microarnmeter-type indicator 32. The battery 3o, resistor 3I, and meter 32 are advantageously mounted in a separate casing or control box indioated by dotted .lines 33.

By varying the resistor 3| to a point where the meter 32 indicates a predetermined current for a given size of apparatus and type of water to be treated, the treating voltage between the anode i3 and the cathode I6 may be adjusted to a desired critical value to insure eicient operation and optimum effects of the device. EX- perience has shown that treating voltages of less than about 12 millivolts will produce satisfactory results. lf desired, of course, other means for adjusting the operating voltage may be employed such as a millivoltmeter directly connected to the electrodes I0 and I3.

Although most satisfactory results have been obtained by using the outer electrode as the cathode which may be suitably grounded through the water or pipe line, a reversal of the polarity is possible, in which case the outer electrode will be the anode and the inner electrode functions as the cathode. In the first case, as shown in the drawing, the outer electrode may consist of iron, while the inner electrode is preferably of brass, or both electrodes may advantageously consist of brass or an equivalent metal to prevent corrosion and other undesirable chemical effects in connection with the foreign matter or impurities present in the water being treated.

If the inner electrode is used as the anode, satisfactory results have been obtained in reducing or eliminating the effects of hardness of water and in order to insure optimum results, the device is advantageously so constructed as to cause a maximum of the water being treated to come in 'contact or close proximity with the electrodes. This may be accomplished by the use of as close a spacing distance as possible between the electrodes (about 1/8 to 1A" or more, depending upon the size of the apparatus) and by the employment of perforated electrodes such as shown in the drawing. An alternative means for increasing the exposed electrode surface, especially that of the anode in Figure l, consists in providing the latter with longitudinal grooves or flutes and/or by suitably roughening or etching the surface of the electrodes by Sandblasting, chemical etching, or in any Vother suitable manner.

Referring to Figure 2, there is shown a device similar to that of Figure l1 and embodying ent types or characteristics of the water being treated is not required, resulting both in great simplification of the apparatus and ease of installment, as well as a complete elimination of supervision during use.

There is provided for this purpose a special series resistance funit for dropping the voltage ofthe battery or other supply source to the desired treating or operating Voltage between the main electrodes IB and I3, the resistance of said unit varying in the same manner as the resistance of the water being treated, whereby to result in a constant resistance ratio or division ofthe battery voltage upon the voltage drops across the series resistance and the drop across the treating electro-des of the device, respectively. As shown diagrammatically in the drawing, the auxiliary or series resistance is connected to the tube or conduit 35 of the device and comprises a column or volume of water passing between or being enclosed by a pair of electrodes 36 and 3l suitably mounted within an insulating tube 38 of glass or other material connected to the pipe 35 through inlet and outlet members in the form of bent or angular metal tubes 40 and 4I or the like, respectively, in such a manner as to cause a portion of the water through the conduit 35 to flow through the thus-provided by-pass and in contact with the electrodes 36 and 3l, as indicated by the arrows in the drawing As a result of the main liquid gap formed by the electrodes I and I3 being included in the conduit extending from the opposite ends thereof, the entire liquid stream to be treated will be restricted to the main liquid gap in exposed contact with the electrodes Ill and I3, the auxiliary liquid gap formed by the electrodes 35, 31 being spaced and substantially electrically independent from said main liquid gap.

-In the example shown, the electrode 36 is connected to the positive pole of the battery r dry cell 42 through a suitable electrical conductor or wire and. the electrode 31 is connected in series with the gap between the main treating or operating electrodes I3 and I0 of the device to the negative pole of the battery, or a suitable tappoint of an adjustable potentiometer resistance 43 shunted across the battery terminals, as shown in the drawing. Accordingly, the auxiliary liquid gap formed by the: electrodes 36 and 3l is electrically connected in series with both the main liquid gap formed by the electrodes I0 and I3 and the voltage source 42, 43, in the manner of an electric voltage divider or potentiometer circuit.

Accordingly, therefore, since the specific resistance of the water gap between the auxiliary electrodes 36 and 31 varies in the same manner as the speciiic resistance of the main liquid gap between the electrodes I0 and I3, it is seen that the division of the battery voltage upon the auxiliary resistance between electrodes 36 and 31 and the main resistance between electrodes IIJ and I3 will remain constant, depending merely on the geometric design, that is, the relative space or volume enclosed by the electrodes IIJ and I3, on the one hand, and by the electrodes 36 and 31, on the other hand.

Thus, assuming, for instance, a battery or other supply voltage of 1.5 V., such as supplied by a standard dry cell, and a desired operating voltage of 1.5 mv. for the treatment to be maintained` between the main operating electrodes I0 and I3, all that will be necessary to insure thel proper operating Voltage is to design the ratio between spacing and area of the electrodes 36 and 31 of the series water resistance unit to be equal to times the ratio between the spacing and area of the electrodes I0 and I3. 'I'he desired operating Voltage of 1.5 mv. will then be applied at all times and under all operating conditions to the electrodes I0 and I3 of the treating unit without any further controls or adjustments and independently of the hardness or other characteristics and changes of the particular water being treated, as will be readily understood from the above.

If, for one reason or other, it is desired to vary the operating voltage with a given design of apparatus, such as from 1.5 mv. to, say, 3 mv., a corresponding initial voltage may be derived from a suitable tap of the potentiometer 43. Alternatively, the device may be designed for any other operating voltage to be provided by a standard' battery or dry cell by the proper relative construction and design of the series resistance unit in a manner which will be evident from the above.

In the design of a device afore-described and shown in Figure 2, care should be taken that the shunt or parallel resistance path from the electrode 36 directly to the outer electrode or cathode I0 through the tubes 40, 4I and 35 has a value which is large compared with the resistance of the water column between the electrodes 35 and 3l.

In the example shown, the resistance of-the water column enclosed by the electrodes 36 and 31 is shown to be a small fraction of the resistance between each of said electrodes and either of the connecting tubes it and 4I, whereby to cause the major portion of the current to pass between the electrodes 36 and 3l to the main ,A electrodes I3 and IEI and back to the negative terminal of the battery and to render the by-pass or shunt current returning directly to the battery through members 4I! or 4I, 35 and II), of negligible value. Furthermore, by making tubes 40 and 4I of insulating material, the relative resistance of the direct return or shunt path to the cathode may be further increased.

Referring to Figure 3, there is shown a modiied construction of a device according to the invention, being of simple and compact design and suitable for direct attachment to a water faucet or the like and embodying a dry cell of standard design and a series resistance structurally embodied therein. The numeral represents an outer tubular casing forming the cathode of the device and having an upper conically-shaped end of lesser diameter designed to cooperate with a screw-on type cap 46 and resilient gasket 4l to enable its quick connection to a faucet or other water supply pipe or tube 48.

The inner electrode or anode 50 has the form of a metal cup concentrically mounted within the cathode 45. For this purpose, the lower open end of the cup 50 is closed in a liquid-tight manner by a plug or stopper 5I preferably consisting of rubber or an equivalent material and forced into or otherwise mounted in the cup 53. The outer surface of the plug 5I has secured to it a metal disk 52 such as by meansof a bolt 53 having a nut 54 engaging the inner surface of the plug,

7. said" bolt being threaded intel a center bore ofthe disk 52.

The entire sub-assembly comprising the anode cup B, resilient plug 5l, and disk 5.2 is at rst mounted Within the internally threaded conically-shaped cap 55 terminating in a tube or outlet 55 by screwing the peripherally threaded disk 52 into the cap 55, whereupon the latter is, in "turn, screwed onto the lower end of the cathode casing 5, as shown in the drawing. Disk 52 is provided with suitable apertures or perfora tions 5E to enable the passage of water from the inlet pipe 48 in between the electrodes 45 and 58 and out through the outlet 55, as indicated by thearrows in the drawing.

ln order to prevent acci-dental short-circuits between the electrodes i5 and 5d, an insulating spacer ring 57 of rubber or the like, or any equivalent spacing means, such as a coating of varnish, is shown mounted at or near the upper closed end of the cup 5i), such as by a crimping connection or in any other suitable manner.

The space inside the cup or anode 56 closed in Vwater-tight manner by the plug 5l is suitably utilized to accommodate a dry cell 5 8 of the knownashl-ight or similar type available on the' market and surrounded by an insulating tube 6i. The lower or negative pole ci the cell @il formed in a known manner by its metallic casing, is in direct contact connection with the nut 54` and accordingly also with the cathode through the continuous conducting path formed by the bolt 53 and metallic disk 52. The positive pole or central terminal of the drycell 6G engages a resilient contact or terminal of a resistance element 63 embedded in a suitable wafer-shaped insulating` casing and having a cooperating terminal also in the form of a resilient contact and engaging the inner end or bottom of the cup 55 forming the anode of the device, in a manner well understood from the above. In order to insure a good electrical connection of the cathode #i5 to ground by way of the inlet pipe d8, gasket il may consist of electrically conducting rubber or an equivalent material or it may be in the form of a slit vmetal ring or equivalent conducting element.

There is thus provided b y the invention a treating unit of the type described which is both compact and simple in construction, which may be easily and readily connected to an existing water supply such as an ordinary water faucet and which may be quickly and readily disassembled and reassembled for exchange of the battery or dry cell, or to replace the series resistance to conform with any existing conditions or requirements. For practical purposes, a set of resistors 6 3 of standard ranges may be provided, designed ior the most common types of water or ranges of hardness to be expected, and the proper resistance unit dropped in the cup 59 before insertion of the dry cellduring assembly of the device.

In order to insure efficient contact to the battery terminals, anadditional resilient spacer or Contact element in the form of a coil spring, etc., may be provided and inserted between the nut 54 and the cathode or metal casing of the dry cell 60. Moreover, resistor B3 may be adjustable in any suitable manner to avoid the necessity of a large number of units if widely varying operating conditions and characterizations of 'the water being treated are anticipated.

Figure 4 shows an elevational View of va modied unit similar 'to that shown in Figure 3 .and em- `passage or opening EB. ging by dirt or other foreign matter, and to pre-" body-ing constructional means, according to. theV crimping and/or spinning over the edge of the cup, as shown, or in any other suitable manner to produce a water-tight joint. Member is of disk shape and member t5 represents an inverted cup suitably dovetailing with the member 6.5 Aand clamped into liquid-tight engagement therewithv and with the anode cup by the provision of suit-A able gaskets such as shown at 65 and readily understood from the drawing. Member 65 has. a!-

central perforated extension E? to cause a steady stream of water to flow through the inner space thereof and out through a suitable lateral outlet in order to prevent clog-- vent direct electr-ical path to the outer container,

the extending member G5 is covered with -a metal screen "it held in any suitable manner such as by crimping and having a portion extending and being connected to the anode 5% and also covering the outlet opening 6B. In the example shown, the l connection to the anode is eiected by clamping the end of the screen member between the mem- .ber 5,6 and the inturned or spun edge of the anode There is, furthermore, shown in Figure 4 a rivet 'ii or other conducting element passing from the inner to the outer face of the insulating disk 65 in a water-tight manner and being in contacting engagement with the positive terminal of the dry cell '63. T-here is established in this manner a water resistance path from the positive pole of the dry cell by way of the rivet 'H through the water column in the extension 57 to the screen 10 and the Ianode 5t, on the one hand, and by way of the parallel path through the outlet opening 58, on the other hand. The design of these water resistance paths is such that the combined voltage drop therethrough from the dry cell 6D to the screen iii will result in the desired treating vor operating voltage between the main electrodes #l5 and 5@ for a given nXed `battery. voltage in a manner which will be evident from the above.

Referring to Figure 4A, there is shown a fractional view of Figure 4, illustrating a modification thereof to provide an adjustable water series resistance. For this purpose there is provided an exchangeable tubular member 13 made `of glass, Bakelite or other insulating material having a desired 'inner diameter and inserted in the vertical bore or` channel of the insulating member 61. All that is necessary, in this case, to obtain a diierent series resistance is to remove the top o the screen and to .drop a different tube 13 having a suitable inner diameter to result in a.

vnegative pole to the casing or cathode 45.

'concentric with the main casing or cathode as shown'in the previous modification. This construction has the advantage of enabling the exchange of the dry cell without completely dis- V assembling the device, as will be vfurther understood from the following.

For this purpose, the lower open end of the anode cup l) is formed with an out-turned edge Vor flange 'i8 surrounded by a resilient 'rubber washer 'I9 or troughor channel-shaped crosssection and clamped against an inner shoulder provided by the lower enlarged portion of the cathode or casing 45 by the aid of a clamping ring '83 engaging and screwed into the internally threaded enlarged end part of the casing 45. A further washer 8| may be inserted to insure a water-tight joint. The dry cell B0 is'then inserted -intothe anode cup 5l! and the lower end of the cathode closed by a screw-on type metal cover or disk 82. Y A compression spring 83 interposed between the latter and the bottom of the battery 60 results in an electric contact connecting the In order to prevent accidental short-circuit, a rubber ring or-l the like 51 is shown in a circuminsulating spacer between the electrodes. l

f Figure 6 shows a modication of a device substantially like that shown in Figure 5 but mounted I in an inverted position, that is, with the inlet and outlet being interchanged to enable the mounting -of a microammeter 85 in the cover 62 for adjusting and supervising the operating or treating voltage. Microammeter S5 is suitably connected `in series with the electric circuit, together with a variable resistance (not shown) for controlling the operating voltage in a manner shown by the diagram rin-Figure l and readily understood from the above.

Referring to Figure 7, there is shown a fractional view of a device of the type according to Figure l, including a different structural ernbodiment of an adjustable water resistance in accordance with the invention- For this purpose, member I4 is shown mounted in inverted position and the inner electrode i3 extended in the opposite direction in the manner shown. An internally threaded insulating bushing B8 having a head 83 consisting of a suitable molded plastic and provided with a threaded metal insert 8l directly mounted therein is screwed in a bore or opening of the outer tube IB in a liquid-tight manner such as by the provision of a suitable gasket, as shown, or the like. The inner end of the bushing 83 extends through an opening in the anode I3 and a threaded metal rod or screw terminal centrally passing through it may be adjusted to varying distances from a central axial extension 9i of the anode-supporting member I4. With the inner member i3 forming a floating or bi-polar electrode, the bolt il and bushings I5 and 2l merely serve as an insulating and liquid tight mounting means for the electrode I3. Furthermore, the extension I 3 of the electrode I3 enclosing the auxiliary electrode or projection 9| forms an electrostatic screen, to prevent a direct return or current iiow between the electrodes ferential groove of the anode cup 5!) acting as' an r35 I0 and 90 and to provide an electric series circuit containing the source 42 and the substantially electrically independent liquid resistanc'es formed by the main liquid gap between the electrodes Ill and I3 and the auxiilary liquid gap formed by the auxiliary electrodes 9U and 9|, respectively.

' In this manner, by the vproper adjustment of the screw terminal Sil, a desired water resistance will be obtained'in series with the battery or source 42 and the main operating electrodes I0 and I3, in a manner readily understood from the above. Once the voltage between the electrodes II) and I3 has been adjusted to a desired value with the aid of suitable electrical instruments, the screw terminal 93' may be permanently fixed or locked by a coating of varnish or in any other suitable manner. No further adjustment or control willthen be needed to insure a proper and constant operating voltage provided the same primary battery or voltage source 42 is employed as is used in the initial adjustment of the device.

As will be understood, the screw terminal need not project beyond the bushing 88 as shown, in which case the Vwater will penetrate into the open bore of the bushing, whereby to substantially increase the adjusting range of the series resistance and making it possible to 'design same substantially independently of the remaining parts.

'While the device according to the invention has been described with specic reference to the electric treatment of water, it will be understood that the same may be employed with equal advantageinl connection with other liquids or iiuids to be' conditioned or treated in the same or a similar manner. Thus, in'generaL'inv the case of mixtures, solutions, suspensions, etc., the electric treatment in-the 'manner described is likely to result in similar effects suchas in preventing'precipitation in an undesirable form such as scale 'or in alecting for preventing other undesirable chemical actions after passing the treating apparatus. It is understood, therefore, that the device as described hereinabove may be used with equal advantage in all such analogous cases of liquid or fluid treatment independently of the lspecial use or i'inal results to be obtained. Thus, even in the treatment of water, the apparatus in one case may be specially intended for preventing scale in connection with boilers or other heating devices, while in other cases the object may be more or less limited to the improvement in the use of soaps such as in laundries and various other applications.

While there have been shown and described a few desirable embodiments of the invention, it is understood that this disclosure is for the purpose of illustration and that various changes in shape, proportion and arrangement of parts, as well as in the substitution of equivalent elements for those herein shown and described, may be made without departing from the spirit and scope of the invention, as dened in the appended claims. The speciiication and drawings are accordingly to be regarded in an illustrative rather than a restrictive sense.

I claim: Y

l. A device for electrically treating a liquid stream comprising a pair of spaced main elec-V trodes forming a main liquid gap, a conduit including said gap and extending from opposite ends thereof for restricting the entire liquid stream to be treated to said gap in exposed contact with said electrodes, auxiliary electrode means within said conduit being spaced from said main liquid gap and substantially electrically independent therefrom, the liquid gap formed by said auxiliary electrode means having a cross-section and length toA provide an electric resistance being a substantial multiple of the electric resistance lof said main liquid gap, and series circuit means for connecting said main electrodes and said auxiliary electrode means to a voltage source.

2. A device for electrically treating a liquid stream comprising a pair of spaced main electrodes forming a main liquid gap, a conduit including said gap and extending from opposite ends thereof for restricting the entire liquid stream to be treated to said gap in exposed contact with said electrodes, a pair of auxiliary electrodes within said conduit being spaced from said main liquid gap and substantially electrically 'independent therefrom, the liquid gap formed by said auxiliary electrodes having a cross-section and length to provide an electric resistance being a substantial multiple of the electric resistance of said main liquid gap, and series circuit means -fory connecting said main electrodes and said f auxiliary electrodes to a voltage source.

3. A device for electrically treating a liquid stream comprising a .pair of spaced inner and -outer main electrodes, the latterk substantially enclosing the former to form a main .liquid gap, a conduit including and extending from opposite ends of said outer electrode for restricting the entire liquid stream to be treated to said gap in exposed contact with said electrodes, anexten- -vasubstantial multiple of the electric resistance of said main liquid gap, and means for connecting a voltage source between said further auxiliary electrode and said outer electrode.

4. A device as claimed in claim 3 `including electrostatic screening means of electrically conducting material connected to said inner elec- 12 trode and enclosing said rst auxiliary electrode,

5. A device for electrically treating a liquid stream comprising a pair of concentric cylindrical inner and outer main electrodes, the latter substantially enclosing the former to provide a main liquid gap, a conduit including and extending from the opposite ends of said outer electrode for restricting the entire liquid stream to be treated to said gap in exposed contact with said electrodes, a iirst auxiliary electrode connected to and axially extending from said inner electrode, a second auxiliary electrode insulatingly mounted and passing through said conduit, said auxiliary electrodes forming an auxiliary liquid gap spaced and substantially independent from said main liquid gap, said auxiliary liquid gap having a cross-section and length to provide an electric resistance being a substantial multiple of the electric resistance of said main liquid gap, and means for connecting a voltage source between said outer electrode and said second auxiliary electrode.

6. A device as claimed in claim 5 including a perforated conducting screen connected to said inner electrode and enclosing said first auxiliary electrode, to substantially prevent current now between said .second auxiliary electrode and said outer electrode.

WILLIAM DUBILIER.

REFERENCES CITED The following references are of record in the ile of this patent:

UNrrED STATES. PATENTS Number Name Date 525,304 Woods Aug. 28, 1894 661,340 Grever Nov. 6, 1900 671,946 Holland Apr. 9, 1901 820,113 Hinkson Mayv 8, '.1906

935,457 Bridge Sept. 28, 1909 1,065,361 Hartman June 24, 1913 1,403,102 Perkins- Jan. 10, '1922 1,930,830 Twombly Oct. 17, 1933 2,121,875 Kruse June 28, 1938 2,207,583 Freeborn July 9, 1940 2,299,964 Crouch Dett 27, '1942 

